When building any type of complex product, one must use reliable subcomponents in order to create a final product that will operate properly and operate reliably. Thus, every subcomponent to be used in a complex product should be carefully tested before it is installed into another product.
Wire conductors are used in almost every electronic product. In general, wire conductors are very reliable. However, extremely small diameter wire conductors often contain defects that may cause the extremely small diameter wire conductor to not fully conduct properly or not conduct at all.
Extremely small diameter wires may be created using a process that covers a metal filament with a glass coating in a process known as the “Taylor-Ulitovski process”. Using the Taylor-Ulitovski process, one may produce fine glass-coated metal filaments that are only a few micrometers in diameter. These glass-coated metal filaments are often referred to as microwires.
In the Taylor-Ulitovski process, a borosilicate (or other) glass tube contains a cylindrical plug of metal which may be, but is not limited to copper, platinum, or gold or alloys thereof. In most variations of this process, the metal is heated by inducing eddy currents by means of a rapidly-changing magnetic field, typically produced with an electromagnet. The metal is inductively heated to the point that it begins to flow with gravity, and as the melting point of the glass is lower, the molten glass also flows and coats the metal. The glass-coated metal filament that begins to form due to gravity is then spooled and drawn at a carefully controlled tension and speed to yield a given diameter filament. The Taylor-Ulitovski process has several important parameters, including but not limited to magnetic field power, composition of the metal and the glass, pulling tension and speed, and environmental temperature and humidity. The large process parameter space and the process' sensitivity to small changes in those parameters means that expert operators and experience are needed to yield high-quality microwire, and even then discontinuities in the inner conductor of the microwire occur on the order of once per meter or more.
Since the process of creating extremely small diameter microwires is very difficult, the produced microwires may contain minor or significant defects. For some applications, microwires with minor defects can still be used. Significant defects can render a section of microwire useless. Thus, to ensure that any product created with very small diameter microwire operates properly, the microwire should be very carefully tested and graded. It would therefore be desirable to implement systems and methods for testing microwires that can identify defects within the microwire and where those defects are located in the microwire. In this manner, significantly defective sections of microwire can be discarded and sections with minor defects can be graded for applications that can handle the minor defects.
The FIGs. depict various embodiments for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that other embodiments of the structures and methods illustrated herein may be employed without departing from the described principles.